• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Dual Pusher Blunt Nose Versa? Why not?

BankNYank!

New member
Mentor
#1
First off I just have to say, I submitted this as an article on the FT main web site and I have been waiting for a week to get it approved. To be honest, I just got tired of waiting. Thats when I started looking around on the forums here for the first time and found someone had a similar issue and was told to just post it to the forum. So this is pretty much an exact copy of my article that's still waiting for approval. I hope you guys like it!

When I watched the "Let's Fly" video for the Blunt Nose Versa I noticed this HUGE gap between the control surfaces and I instantly knew I had to do something about that so I went in the shop and got to work.

While building this thing I remembered a video where a guy (MyGeekShow) tried to use thrust vectoring to act as a kind of "rudder" on a delta wing and my mind went to differential thrust. I didn't have all the details worked out for differential thrust by the end of the build but I went and maidend my creation anyway without it. It flew really nice and was very stable from the beginning. A little trimming was all it took and it was good to go.

After the maiden, and a few additional successful flights that day, I came home with the idea of using differential thrust on my DX6i still nagging in the back of my mind. So I hopped online and did some digging and came across an article (and I really wish I could find it again so I could give the guy credit) where someone suggested using a v-tail mixer since the DX6i has some kind of issue with binding differential thrust to the rudder channel. So I ran out to the shop and threw it together using a v-tail mixer.

I have added some pictures of my work and a video at the bottom demonstrating the differential thrust. Please comment and let me know what you think. Also, I'm very new to the RC hobby so any suggestions would be great!



I put the esc's as far forward as I could get them to help balance out the weight of having two motors in the back.


I'm pushing the Blunt Nose Versa with a pair of Suppo 2208/14 1450kv motors swinging 7x4 props. (Not the cw and ccw 8x4's shown in this picture)


I used magnets to hold the hatches shut and nylon control horns for handles.


I'm running everything on two 3s 2200's in parallel with that adapter and wire mess.


To get differential thrust on my DX6i without mixing any channels I used a v-tail mixer. You can see where it is plugged in at rudder and throttle.

Heres the differential thrust in action on my DX6i.

When I maidend my build I felt the whole setup was way under powered and found myself using 3/4 to full throttle most of the time. The only cw and ccw props I could find close to what I was looking for as a set in stock at HK (USA) were 8x4's. With these motors (Suppo 2208/14) I have found that 7x5's seem to work the best so I went home and threw the concept of counter-rotating props out the window and put on a pair of 7x5's. I was worried about unwanted torque roll with two motors spinning the same direction but couldn't wait for my next chance to go flying again so I could try it out. Today was the day. I'm happy to announce, no torque issues at all, I don't think I even changed my trim from the maiden, and the differential thrust does work! My wing isn't going to be doing any knife edges anytime soon but I was able to navigate using only elevator and differential thrust and was able to do so quite well. I've never flown a plane with rudder and ailerons (I like planes that bank and yank) so I'm not really sure what all can be done with a rudder but I was able to get my wing into a verticle stall then decide if I wanted it to fall left or right using differential thrust. I can also get it to yaw a little if I give it some differential thrust in one direction and push the ailerons (elevons) in the opposite direction. But I don't know if thats the proper way to get a plane to do a flat yaw and I've had no practice doing it. I honestly expected to be able to get it to yaw more but I don't know if the problem is with the differential thrust or my inexperience.

When I fly a plane I like to be able to cruise at below half throttle. The issue I had with the 8x4 props caused me to pack a couple Suppo 2212/10's in my backpack just in case changing the props didn't help enough. I liked the difference the 7x5's made on the 2208/14's and I was at a good cruising speed right around half throttle but I brought the 2212/10's so I had to try them. I have to say, they worked very well and I enjoyed using them very much. With those motors verticle wasn't unlimited, but it took a long time for the Wing to stall. They would be my perminate motors to use on this Wing however, using the same size (3s 2200) batteries my flight time seemed to be pretty much cut in half. I want to use this plane for fpv so reduced flight time to me is a bummer.

Lastly, my camera man was unavailable today but I will get some video of the stalls and yaw I can produce with differential thrust soon. If anyone can think of anything else they want me to try using the differential thrust please let me know and I will do my best. And no, it won't do flat spins, at least I haven't been able to get it to do any, but I don't really know how to get it to spin other than just holding the rudder full over and that hasn't worked.
 

makattack

Winter is coming
Moderator
Mentor
#3
Nice! I think you'll find that main site articles take time to get vetted and posted. Thanks for sharing. I love the idea of the twin pusher with differential thrust. Too bad about the reduced flight time. I guess all that weight adds up. I wonder if getting rid of one battery might counter-intuitively get you more flight time. You will need a Y power harness and maybe a larger capacity battery.
 
#4
so, you can plus a Vtail mixer into your rudder and throttle (rx) and the 2 ESC's into the Vtail and get differential thrust? I didn't know it could be done that easy. I thought you had to have a fancy radio to program that function.

if it is that easy, I might want to do a diff thrust setup in the near future.
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#5
yup!

Rudder into the mixer's aileron input, throttle into the mixer's elevator input. As you increase throttle, the signal on both L/R outputs go up together, and as you push the rudder left or right, it increases one channel and decreases the other.

you can still do it via mix on the radio, but you'd need at least three mixes to do it:
- Throttle stick ->aux (to mirror the throttle to the other motor)
- Rudder Stick -> throttle (for one side of the differential)
- Rudder Stick -> aux (for the other side of the differential)

Unfortunatly they crippled the DX6i with only 2 mixes. It's still a nice radio, and it should be capable of doing something like this, but with only 2 mixes your hands are tied.
 
Last edited:

pgerts

Old age member
Mentor
#6
You will not get the real rudder effect when the motors are so close to each other.
It is a big difference if the motors are more like on a normal twin engine plane with a fuselage between the props.
 

BankNYank!

New member
Mentor
#7
Thanks for commenting. I'm glad you like it!

Nice! I think you'll find that main site articles take time to get vetted and posted. Thanks for sharing. I love the idea of the twin pusher with differential thrust. Too bad about the reduced flight time. I guess all that weight adds up. I wonder if getting rid of one battery might counter-intuitively get you more flight time. You will need a Y power harness and maybe a larger capacity battery.
I agree. I think its a combination of the extra weight of the motors and the added current draw. The 2208/14's draw 130 Watts each and weigh 36g each while the 2212/10's draw 180 Watts each and weigh 47g each. I made a 'Y' power harness, its in one of the pictures, I'll just have to take off the parallel adapter and I can run one battery, easy peazy. I like the idea of one larger battery. Payday is tomorrow and I've been weighing my options. Literally.

so, you can plus a Vtail mixer into your rudder and throttle (rx) and the 2 ESC's into the Vtail and get differential thrust? I didn't know it could be done that easy. I thought you had to have a fancy radio to program that function.

if it is that easy, I might want to do a diff thrust setup in the near future.
Yes, its that easy, just like Craftydan says, and cheap. Heres a link to the v-tail mixer I'm using: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=36732

I bought these mixers so I could put them in my Versa Wing's and buddy box my DX6i with a DX5 so friends and family can get a little flight time and experience the joy of the hobby. I don't like using them for their intended purpose myself because they produce mad throws that are hard to calm down and are "stuttery". But they seem to work very well as a differential thrust mixer. I have now had multiple flights on my Blunt Nose Versa with the v-tail mixer installed and no issues out of it at all.

yup!

Rudder into the mixer's aileron input, throttle into the mixer's elevator input. As you increase throttle, the signal on both L/R outputs go up together, and as you push the rudder left or right, it increases one channel and decreases the other.

you can still do it via mix on the radio, but you'd need at least three mixes to do it:
- Throttle stick ->aux (to mirror the throttle to the other motor)
- Rudder Stick -> throttle (for one side of the differential)
- Rudder Stick -> aux (for the other side of the differential)

Unfortunatly they crippled the DX6i with only 2 mixes. It's still a nice radio, and it should be capable of doing something like this, but with only 2 mixes your hands are tied.
I don't know anything about mixing (I'm still pretty new to the hobby) but thats pretty much what I read about the DX6i also. Thanks for explaining the issue with the DX6i and the proper way to mix diff thrust in other radio's!

You will not get the real rudder effect when the motors are so close to each other.
It is a big difference if the motors are more like on a normal twin engine plane with a fuselage between the props.
That makes sense. The further out on the wing the motors are the further they are from the plane's cg which gives the motors more leverage to yaw the plane. Thanks for the input!
 
Last edited:

Slowlane

Junior Member
#8
I was just thinking about this the other day and stumbled on to this thread.. I know it has been a while but how has it worked out for you so far?
 
#9
Only advice I can give is don't cut away Amy of the heat shrink on those turnigy esc's. I tried it on my 30A and the heatsink fell off. I didn't cut much of the heat shrink off either.

it must be the only thing holding it together.
 

BankNYank!

New member
Mentor
#10
I was just thinking about this the other day and stumbled on to this thread.. I know it has been a while but how has it worked out for you so far?
The plane fly's great! I still have it though I've removed the motors to use on other projects. The differential thrust didn't work very well but it was fun to experiment with! The only thing I would really recommend is reenforcing the nose and front door/bay cover hinge. I fly mine a little heavy with two 3s 2650's in the nose and a couple hard landings have loosened up the foam in the nose a little but nothing serious and the hinge point on the front bay door has started tearing.

Other than that I still love the plane and think it would make a great fpv platform!

Only advice I can give is don't cut away Amy of the heat shrink on those turnigy esc's. I tried it on my 30A and the heatsink fell off. I didn't cut much of the heat shrink off either.

it must be the only thing holding it together.
If that's the case I imagine the thermal paste and heat shrink are the only things holding the heat sink on. Both those esc's are still on that plane but I'll keep that in mind should I ever decide to use them for anything else. Thanks for the tip!
 
#11
Hi, I am building the FT Mini Guinea, I am using a DX6i. I tried the mixing option for this but hadn't fine tuned it.
Since I had a V-tail mixer I thought I would try it.
It worked GREAT. I am very happy with this method and will maiden the plane soon.
Thanks a lot,
LooseBruce
 

BankNYank!

New member
Mentor
#12
Hi, I am building the FT Mini Guinea, I am using a DX6i. I tried the mixing option for this but hadn't fine tuned it.
Since I had a V-tail mixer I thought I would try it.
It worked GREAT. I am very happy with this method and will maiden the plane soon.
Thanks a lot,
LooseBruce
I'm really glad you were able to use the v-tail mixer idea for your Mini Guinea. Would love to see some video of it in use!

One word of caution. Please remove your props when testing your v-tail mixer for differential thrust. I hooked mine up backwards one time and this is what happened.